CD8+ lymphocytes play an important role in host immunity to viruses and other intracellular parasites. Antiviral CD8+ T cells recognize MHC class I molecules bound to peptides derived from a cytosolic pool of viral proteins. The induction of antiviral CD8+ T cell responses is potentially limited by the rates at which peptides are generated from full-length gene products and the rate at which peptides are transported into the ER by TAP, the MHC-encoded peptide transporter. In an effort to develop more efficient vaccines for eliciting CD8+ T cells, we created a number of recombinant vaccinia viruses that express antigenic peptides in the absence of flanking residues or with an amino terminal extension that targets the peptides to the endoplasmic reticulum. Testing of these recombinants indicates that these recombinants more efficiently elicit CD8+ T cell responses than traditional recombinants expressing full-length gene products.